Limited-cut-off steam engine



July 1, 1930. n'us ET AL I 1,769,809

LIMITED CUT-OFF STEAM ENGINE Filed Nov. 16, 1927 AORNEYS Patented July l, 193% GFICE HUBER! J. TITUS, 0F PETERSON, NEVJ JERSEY, AND JOHN S. VJALLIS, OF NEW YORK, N. Y., ASSIGNORS TO FRANKLIN RAILYVAY SUPPLY COMPANY, OF NEW YORK, N. Y.,

A CGRPORATION 0F DELAWARE LIMITED-GUT-OFF STEAM ENGINE Application filed November 16, 1927. Serial No. 283,577.

This invention relates to what is known in the art as a limited cut-0d steam engine and is particularly applicable to limited cut-off locomotives.

In locomotives of this type the valves and operating mechanism therefor are arranged so that in what would ordinarily be full gear position cut-ofi will occur at the main steam ports at some percentage of the stroke of the piston materially less than heretofore customary, say for example With such an arrangement of the valves and valve operating mechanism there are, of course, positions in which the engine may stop where the turning moment is insufficient for startin order to effect a start it has been customary to provide what are known as auxiliary or starting ports adapted to deliver steam to the cylinders after cut-off at the main port. These starting ports are ordinarily of relatively small capacity with the icea in mind that as the speed of the engine increases the amount of steam delivered therethrough will gradually become of less and less consequence.

It is now coming to be recognized, however, that in order to have an engine which will be capable of snappy starting it is necessary to make the auxiliary or starting ports of substantial capacity. This makes the flow of steam thru them a matter to be considered at all speeds of the engine especially where no provision is made for preventing pre-admission of the steam thru the starting ports. Preadmission takes place, it will be understood, thru the starting ports before admission at the main ports and becomes a substantial factor in decreasing the power out-put of the engine during the compression period of each stroke of the pistons.

lVith the foregoing in mind the object of our invention can be better understood and it can be stated as involving a means for minimizing the deleterious efiect of pre-ad- Fig. 1 is a vertical longitudinal section thru a portion of the cylinder and valve chest of a steam engine equipped with our invention Fig. 2 is a similar view illustrating another manner in WlllCll the 1nvent1on may be carried out;

Fig. 3 is another similar view illustrating a third way in which our invention may be carried out;

Fig. 4 is a fragmentary view similar to Figs. 1 to 3 inclusive illustrating still another method of carrylng out our lnventlon;

and

Fig. 5 is a fragmentary view of the cylinder and piston of a steam engine illustrating one more way in which we may carry out our invention.

The several figures all represent typical locomotive construction and the invention will be described as applied to a locomotive.

The cylinder 1 is supplied with steam from the valve chest 2 thru the customary main steam passages 3 and 4. The main ports 5 and 6 leading respectively to the passages 3 and 4 thru the valve chest bushing 7 are under the control of the customary piston valve 8. It will be understood, of course, that the valve together with its operating mechanism or valve gear (not shown) is arranged to cut off the main port so that the supply of steam will be continued for a portion only of the stroke of the piston 9 which in this instance, will be assumed to be at Furthermore the valve illustrated is what is known as the inside admission piston type with the exhaust taking place at the ends.

In order to start the locomotive the auxiliary passages and 11 are provided which respectively connect the main passages 3 and 4 with the starting ports 12 and 13, the starting ports being located inside of the main ports 5 and 6 so that they will receive steam after cut-0iI at the main ports.

In the several figures the piston 9 is illustrated as traveling toward the right in the direction of the arrow. The admission of steam thru the passage 4 and port 6 has not yet begun and compression is taking place at the right of the piston 9. But during this period of compression, communication with the source of steam supply can take place thru the port 13 and auxiliar assage 11 since the valve 8 has uncovere t e port 13.

This pre-admission or communication With the steam supply thru the starting port is, of course, objectionable in direct propor tion to the capacity of the starting port.

In order to overcome or minimize the deleterious effect of this pro-admission, we provide means for by-passing the steam to the expansion side (the left-hand side) of thepiston. In the arrangement of Figure 1 this is accomplished by means of the aux illary passage 14 which directly connects the starting passage 11 with the cylinder 1 thru the port 15 in the cylinder bushing 16. At the 0 posite end, of course, there is a correspon ing passage 17 extending from the starting passage 10 to the cylinder thru the port 18 in the cylinder bushing.

This arrangement will cause a slight waste ofhteam which, however, is more than offset by the advantage to be derived by minimixing theetfect of pro-admission. Furthermore, at very high speeds of the engine both pre-admissionland wastage are of materially less consequence and at starting some wastage may be permitted in order to obtain the advantages of quick and snappy starting.

The same principle is involved in each of the other figures in the drawing although the method employed in each instance is slightly dillcrent. In Fig. 2 the by-pass 19 consists of a groove or passage cut in the outer face of the cylinder bushing. In Fig. 3 it consists of a passage 20 which connects the main passage 4 with the cylinder on the expansion side of the piston. In Fig. 4 the passage 21 consists of a groove or channel on the inside of the cylinder bushing extendmg between the main passage 4 and the port 15. In Figure 5 a pipe 22 is provided on the outside of the cylinder which connects the port 15 on the expansion side of the pisto; with another hole 23 on the compression si e.

We claim:- 

